fevo-08-00225 July 15, 2020 Time: 8:31 # 1 ORIGINAL RESEARCH published: 14 July 2020 doi: 10.3389/fevo.2020.00225 Testate Amoeba Species- and Trait-Based Transfer Functions for Reconstruction of Hydrological Regime in Tropical Peatland of Central Sumatra, Indonesia Valentyna Krashevska1*, Andrey N. Tsyganov2,3, Anton S. Esaulov4, Yuri A. Mazei2,3, Kartika Anggi Hapsari5, Asmadi Saad6, Supiandi Sabiham7, Hermann Behling5 and Siria Biagioni5 Edited by: 1 J.F. Blumenbach Institute of Zoology and Anthropology, University of Göttingen, Göttingen, Germany, 2 Department of Vincent Jassey, General Ecology and Hydrobiology, Lomonosov Moscow State University, Moscow, Russia, 3 A.N. Severtsov Institute UMR 5245 Laboratoire Ecologie of Ecology and Evolution RAS, Moscow, Russia, 4 Department of Microbiology, Epidemiology and Infectious Diseases, Penza Fonctionnelle et Environnement State University, Penza, Russia, 5 Department of Palynology and Climate Dynamics, University of Göttingen, Göttingen, (ECOLAB), France Germany, 6 Department of Soil Science, University of Jambi, Jambi, Indonesia, 7 Department of Soil Science and Land Resource, Bogor Agricultural University (IPB), Bogor, Indonesia Reviewed by: Bertrand Fournier, University of Potsdam, Institute of Tropical peatlands play an important role in carbon storage and in water regulation Environmental Science and Geography, Potsdam, Germany on a landscape level. However, our understanding of their ecology and long-term Simon Van Bellen, hydrological dynamics remains limited. Transfer functions, constructed on the basis Université de Montréal, Canada of biological indicators (proxies) with known ecological preferences, allow us to infer *Correspondence: past environmental conditions and serve as a basis for prediction of future changes in Valentyna Krashevska [email protected] peatlands. Here, we use testate amoebae to develop the first species- and functional trait-based transfer functions for the Southeast Asia. This provides a valuable tool Specialty section: for future reconstructions of past hydrological changes in tropical peatlands, their This article was submitted to Paleoecology, development, and climatic changes. Surface samples for testate amoeba analysis were a section of the journal taken in various biotopes along two transects across the Sungai Buluh peatland in Frontiers in Ecology and Evolution Central Sumatra. The following environmental characteristics were measured: water Received: 14 April 2020 Accepted: 18 June 2020 table depth (WTD), light intensity, pH, total C and N concentrations. The analysis of the Published: 14 July 2020 surface samples revealed 145 morphotypes of testate amoebae belonging to 25 genera. Citation: A significant fraction of the variance in testate amoeba morphotypes and functional Krashevska V, Tsyganov AN, trait composition was explained by WTD and pH. The wide WTD range (0–120 cm) Esaulov AS, Mazei YA, Hapsari KA, Saad A, Sabiham S, Behling H and seems more valuable for reconstruction than the extremely short pH gradient (2.5–3.8). Biagioni S (2020) Testate Amoeba Thus, transfer functions were developed only for WTD, based on weighted averaging Species- and Trait-Based Transfer Functions for Reconstruction model for morphotypes and multiple linear regression for functional traits. Both species- of Hydrological Regime in Tropical and trait-based model have a predictive ability for WTD reconstruction. For traits, the Peatland of Central Sumatra, best performance of the model was reached by including five morphological traits: Indonesia. Front. Ecol. Evol. 8:225. doi: 10.3389/fevo.2020.00225 shell width, aperture shape, aperture invagination, shell shape and shell compression. Frontiers in Ecology and Evolution| www.frontiersin.org 1 July 2020| Volume 8| Article 225 fevo-08-00225 July 15, 2020 Time: 8:31 # 2 Krashevska et al. Testate Amoebae in Tropical Peatlands We discuss the ecology of several taxa and highlight the traits, which reflect hydrological changes in this system. Though the hydrological preferences of some species are similar to those in high and middle latitude peatlands, we argue that latitudinal differences in morphospecies composition and variations in environmental relationships of species require the development of region-specific transfer functions. Moreover, our results indicate that ecological preferences of morphotypes within morphospecies also need to be considered and included in future studies. Keywords: water table depth, protists, shell size, training set, Hylaosphenia, indicator, peat-swamp forest, hydrology INTRODUCTION for example, Amesbury et al.(2016, 2018). However, only few transfer functions were developed for the Southern Hemisphere Tropical peatlands play a crucial role in carbon sequestration, (Wilmshurst et al., 2003; Swindles et al., 2014, 2018a; van Bellen regulating water resources and safeguarding rich biodiversity et al., 2014). In part, this might be due to the fact that information (Page et al., 2011; Posa et al., 2011; Hapsari et al., 2017). on ecological preferences of testate amoebae in tropical peatlands These peatlands, however, are vulnerable to climate changes is extremely limited. However, data obtained from peatlands of and threatened by their extensive conversion into agricultural temperate and polar regions may not be applicable to low-latitude production systems (Page et al., 2011; Miettinen et al., 2012, peatlands (Charman, 1997). 2013). About a century ago, Polak(1933) wrote that the study on Traditionally, the construction of transfer functions is species- peatlands in the tropics was still at an early stage. This statement, based, which is difficult if identification of the taxa is hampered unfortunately, is still true to this day for the Asian tropics, in (Mitchell et al., 2014). Also, the environmental preferences of particular for palaeoecological research in the region (Biagioni many species are not well known and this restricts their use as et al., 2015). Facing the current changes, there is the pressing ecological indicators (Charman, 1997). Alternatively, ecologically need to study these “palaeoenvironmental archives” (Jackson and significant morphological and physiological functional traits Charman, 2010) to evaluate past environmental conditions and to may serve as indicators of the environmental conditions the predict future changes of these ecosystems. However, crucial steps organisms live in Fournier et al.(2015), van Bellen et al. in palaeoenvironmental reconstructions are the development (2017), and Koenig et al.(2018). Thus, functional traits may of a representative present-day organisms-environment training provide powerful links to ecosystem processes and help to set and the application of adequate numerical methods to strengthen the transfer functions approach based on taxonomic model the relationship between the occurrence and abundance information only (Fournier et al., 2015; Lamentowicz et al., 2015; of recent organisms and their environment (Juggins and van Bellen et al., 2017). In recent years, a new approach for Birks, 2012). Using these so-called transfer functions allows reconstructing past environmental conditions based on testate a quantitative estimation of past environmental conditions. amoeba functional traits has been developed and successfully Transfer functions have been frequently developed and applied applied (for details, see Marcisz et al., 2020, submitted). to predict temperature, precipitation, sea level, pH and water However, the approach still needs refinement and this applies table depth based on species composition of pollen, chironomids, in particular to tropical peatlands. Therefore, this study aims diatoms, and testate amoebae in lake and mire sediments across at (1) extending knowledge on testate amoeba communities in many regions (Birks et al., 1990; Gehrels, 2000; Wilmshurst Sumatra, (2) evaluating the relationships among testate amoeba et al., 2003; Charman and Blundell, 2007; Klemm et al., 2013; morphospecies, functional traits and environmental variables, Massaferro and Larocque-Tobler, 2013). and (3) developing species- and trait-based transfer functions for Testate amoebae are common organisms in many mires future palaeoecological reconstructions of hydrological regime. and, due to their test (shell), they are often preserved in peats (Swindles and Roe, 2007; Mitchell et al., 2008a). Diverse shell morphological characteristics and prominent MATERIALS AND METHODS environmental preferences make testate amoebae valuable ecological indicators. Previous studies showed that species Study Site composition of testate amoeba communities are controlled The Sungai Buluh peatland is a protected forested swamp which by surface wetness (often estimated as water table depth), covers an area of 18,000 ha. It is located approximately 19 km pH, temperature and sea-level change (Charman, 2001; from the coastline and 30 km north-east of the city of Jambi in Mitchell et al., 2008a). Central Sumatra with an elevation ranging from 9 to 25 m above A number of transfer functions have been developed based sea level (Hapsari et al., 2017). From the geomorphological and on the relationship between testate amoebae and peatland hydrological point of view, the peatland of Sungai Buluh is an hydrology in the Northern Hemisphere. For summarised studies extensive coastal peat dome, which is delimited by two rivers on transfer functions from North America and Europe see, located to the east and west sides. The mouths of the rivers are Frontiers in Ecology and Evolution|